Printed stubby unbalanced dipole antenna

ABSTRACT

A printed circuit board unbalanced dipole antenna is provided for a wireless communications telephone. Digital and/or transceiver circuits are mounted on a wireless telephone circuit board. In addition, a radiator is formed from a printed conductive line overlying the circuit board dielectric layer, with an end for connection to a transmission line and an unterminated end. To shorten the overall length of the antenna, the radiator is formed in a series of rectangular or zig-zag meanders with a plurality of first sections with a first orientation and a plurality of second sections with a second orientation, orthogonal, or approximately orthogonal to the first orientation. In some aspects, the radiator first sections overlie the dielectric layer first side and the radiator second sections overlie the dielectric layer second side. Then, the radiator first and second sections are connected with a plurality of vias.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to wireless communication antennas and,more particularly, to an unbalanced dipole antenna that is formed on aprinted circuit board of a wireless communications telephone.

2. Description of the Related Art

The size of portable wireless communications devices, such astelephones, continues to shrink, even as more functionality is added. Asa result, the designers must increase the performance of components ordevice subsystems while reducing their size, or placing these componentsin less desirable locations. One such critical component is the wirelesscommunications antenna. This antenna may be connected to a telephonetransceiver, for example, or a global positioning system (GPS) receiver.

Wireless communications devices, a wireless telephone or laptop computerwith a wireless transponder for example, are known to use simplecylindrical coil antennas as either the primary or secondarycommunication antennas. The resonance frequency of the antenna isresponsive to its electrical length, which forms a portion of theoperating frequency wavelength. The electrical length of a wirelessdevice helical antenna is often an odd multiple of a quarter-wavelength,such as 3λ/4, 5λ/4, or λ/4, where λ is the wavelength of the operatingfrequency, and the effective wavelength is responsive to the dielectricconstant of the proximate dielectric.

Wireless telephones can operate in a number of different frequencybands. In the US, the cellular band (AMPS), at around 850 megahertz(MHz), and the PCS (Personal Communication System) band, at around 1900MHz, are used. Other frequency bands include the PCN (PersonalCommunication Network) at approximately 1800 MHz,

the GSM system (Groupe Speciale Mobile) at approximately 900 MHz, andthe JDC (Japanese Digital Cellular) at approximately 800 and 1500 MHz.Other bands of interest are global positioning satellite (GPS) signalsat approximately 1575 MHz and Bluetooth at approximately 2400 MHz.

Typically, better communication results are achieved using a whipantenna, as opposed to the above-mentioned helical antennas. Using awireless telephone as an example, it is typical to use a combination ofa helical and a whip antenna. In the standby mode with the whip antennawithdrawn, the wireless device uses the stubby, lower gain helical coilto maintain control channel communications. When a traffic channel isinitiated (the phone rings), the user has the option of extending thehigher gain whip antenna. Some devices combine the helical and whipantennas. Other devices disconnect the helical antenna when the whipantenna is extended.

The whip antenna has a physical length, when extended, related to theantenna operating frequency. When withdrawn, the whip antenna must fitwithin the constraints of the wireless device chassis. Therefore, as thewireless device chassis decreases in size, the extended length ofconventional whip antennas has necessarily decreased. A shorter whipantenna can be made to operate at the same frequency as longer whipantennas by using higher dielectric constant materials in the antennafabrication. However, the use of higher dielectric constants makes for alower gain antenna, and a poorer performing wireless device.

One popular solution to the above-mentioned length problem has been tofabricate the whip antenna as a wire with a telescoping tube section.When the antenna is withdrawn, the wire section is withdrawn into thetube, with the tube being withdrawn into the chassis. When extended, thecombination of the wire and tube section defines the antenna length.

Many wireless telephones that are noted for their small size still havea whip antenna portion extending from the chassis body, even in thewithdrawn position. This extending portion can become tangled in atrouser pocket or purse as the user extracts the phone to answer a call.One solution to this problem is to wear a belt-mounted holster to carrythe phone, or to mount a belt clip on the phone. However, this solutionat least partially defeats the purpose of making the phone small enoughto be pocketsize.

It is known to use a portion of a circuit board, such as a dc power bus,as an electromagnetic radiator. This solution eliminates the problem ofan antenna extending from the chassis body. However, these radiators areextremely inefficient “antennas”, typically providing poor gain anddirectionality. These types of radiators are also susceptible tocrosstalk from other signals on the board. Further, these types ofradiators can also propagate signals that interfere with digital orradio frequency (RF) on the circuit board. Electromagneticcommunications through these radiators can also be shielded by othercircuits, circuit groundplanes, the chassis, or other circuit boards inthe chassis.

It would be advantageous if an efficient antenna could be developed thatdid not extend out from the chassis body of a wireless phone, as atypical whip antenna does in the withdrawn position.

It would be advantageous if a wireless telephone chassis could be madewith minimal extending portions, such as the extending portionsresulting from the housing of antennas.

It would be advantageous if an efficient antenna could be formed on awireless telephone circuit board.

SUMMARY OF THE INVENTION

The present invention describes a stubby dipole antenna that is printedon a circuit board. More specifically, the antenna can be formed on awireless telephone circuit board that includes digital or RF circuitry.The formation of the antenna of the circuit board reduces the chassisbody form factor by eliminating, or at least reducing, any extensions inthe body associated with the antenna.

Accordingly, a printed circuit board unbalanced dipole antenna isprovided for a wireless communications telephone. The antenna comprisesa circuit board dielectric layer. Typically, there are digital and/ortransceiver circuits mounted in the circuit board. In addition, aradiator is formed from a printed conductive line overlying the circuitboard dielectric layer with a first end for connection to a transmissionline and a second, unterminated end. To shorten the overall length ofthe antenna, the radiator is formed in a series of rectangular orzig-zag meanders with a plurality of first sections with a firstorientation and a plurality of second sections with a secondorientation, orthogonal to, or approximately orthogonal to the firstorientation.

In some aspects, the radiator includes sections overlying the dielectriclayer first side connected to sections on the dielectric layer secondside through a via. In another aspect, the radiator first sectionsoverlie the dielectric layer first side and the radiator second sectionsoverlie the dielectric layer second side. Then, the radiator first andsecond sections are connected with a plurality of vias.

Additional details of the above described dipole antenna are describedbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of the present invention wirelesscommunications telephone system.

FIG. 2 is a partial cross-sectional profile view of the system of FIG.1.

FIGS. 3 a and 3 b are plan view details of the antenna of FIG. 1.

FIGS. 4 a and 4 b are plan views illustrating a two-sided circuit boardaspect of the antenna of FIG. 1.

FIGS. 5 a and 5 b are plan views illustrating a two-sided circuit aspectof the antenna of FIG. 1 with side-alternating first and second radiatorsections.

FIGS. 6 a and 6 b are plan views illustrating a two-sided circuit aspectof the antenna of FIG. 1 with side-alternating first and second radiatorsection combinations.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a schematic block diagram of the present invention wirelesscommunications telephone system. The system 100 comprises a circuitboard 102 including a first portion 104 and a second portion 106. Anantenna 108 is printed on the second portion 106 of the circuit board102, having a transmission line interface 110.

FIG. 2 is a partial cross-sectional profile view of the system 100 ofFIG. 1. The system 100 further comprises a chassis 200 with a body 202.The body 202 is understood to be the main or substantial portion of thephone. For example, the body of a rectangular or brick-shaped phone isthe rectangle. For a flip-phone, the body is the two clamshell halveswhen the phone is opened, or the substantially rectangular shape whenthe phone is closed. As shown, the body 202 is rectangular. The firstportion 104 of the circuit board is substantially encompassed by thechassis body 202. The second portion 106 of the circuit board extendsoutside the chassis body 202. Alternately but not shown, the secondportion 106 can be encompassed by the body 202. The improved form factorcomes at the expense of degraded antenna performance however, as theantenna is partially shielded.

The chassis body 202 has a first side 204, a second side 206, a top end208, and a bottom end 210. The system 100 further comprises a speaker212 mounted to chassis body first side 204 proximate to the top end 208.The circuit board first portion 104 has a length 214 extending from thechassis body first side 204 bottom end 210, to the second side 206 topend 208. The circuit board second portion 106 has a length 216 extendingthrough the chassis top end 208 proximate to the second side 206. Asshown, the chassis 200 includes an extended portion 218 to encompass thecircuit board second section 106.

The circuit board 102 is angled so that the antenna is positioned awayfrom the user's head during use. The user's head (ear) is likely to benext to the speaker 212. The position of the user's head proximate tothe antenna can interfere with antenna performance. The angled circuitboard alleviates this concern.

Returning to FIG. 1, in some aspects a transceiver circuit 112 ismounted on the first portion 104 of the circuit board with an antennaport 114 connected to the antenna transmission line interface 110. Thetransceiver circuit 112 includes receiver and transmitter circuitry suchas amplifiers, filters, oscillators, and mixers. In other aspects,digital circuitry 116 can also be mounted on the first portion 104 ofthe circuit board. Not shown, the first portion 104 of the circuit boardcan also include power supply circuitry, display circuitry, and/or akeypad. It should be understood that the present invention antenna isable to provide high performance without the necessity of being formedon a separate, single purpose antenna circuit board. Substantial costsavings can be realized by combining telephone circuits on a singlecircuit board. Alternately but not shown, the system may include two ormore circuit boards to reduce the overall form factor of the telephone,with the antenna mounted on one of the circuit boards that also includestransceiver, digital, or power supply circuitry.

FIGS. 3 a and 3 b are plan view details of the antenna 108 of FIG. 1.The antenna 108 is an unbalanced dipole antenna. Considering either FIG.3 a or 3 b, the antenna 108 includes a radiator 300 formed from aprinted conductive line 302 overlying the circuit board second portiondielectric layer with a first end 304 for connection to a transmissionline and a second, unterminated end 306. The lines can be formed from anetching process that selectively removes portions of a metal claddingoverlying the circuit board. Alternately, the conductive lines can beformed through a metal deposition process.

Typically, the antenna radiator 300 has an effective electrical lengthof approximately a quarter-wavelength odd multiple at the operatingfrequency. That is, a wavelength of (2n+1)(λ/4), where n=0, 1, 2, . . .. The length of the radiator is a combination of the various meanderingsections considered in light of the dielectric constant of the circuitboard dielectric layer, as is well known in the art. In other aspects,the antenna 108 can be different length than a quarter-wavelength oddmultiple. Such a situation may occur, for example, when the antenna isexpected to operate over a wide bandwidth or multiple bandwidths.

The antenna radiator 300 includes a plurality of first sections 308 witha first orientation 310 and a plurality of second sections 312 orientedwith a second orientation 314, that can be orthogonal, or approximatelyorthogonal to the first orientation 310. When the first and sectionsections 308/312 are orthogonal, coupling between the sections can beminimized, permitting the antenna to be made “stubby” withoutsubstantially degrading the antenna performance. The sections can alsobe oriented so that they are not orthogonal, further reducing the formfactor of the antenna at the expense of performance, which is degradedby increased coupling between radiator first and second sections.

As shown in FIG. 3 a, the antenna radiator 300 is formed in a pattern ofmeandering rectangular lines. As shown in FIG. 3 b, the antenna radiator300 is shown in a pattern of meandering zig-zag lines. The invention canbe enabled with other patterns or shapes, FIGS. 3 a and 3 b are merelyexemplary.

FIGS. 4 a and 4 b are plan views illustrating a two-sided circuit boardaspect of the antenna 108 of FIG. 1. The circuit board second portion106 dielectric layer has a first side 400 that can be seen and a second,opposite side that cannot be seen in the figures. Further, at least oneconnection via 402 exists between the dielectric layer first side 400and the dielectric layer second side. The vias can be formed through aprocess that drills holes through the dielectric and plates the holeswith a conductive material. Alternately, the vias can be any means thatpass through the dielectric layer to electrically connect to the firstand second sides. The antenna radiator 300 includes sections overlyingthe dielectric layer first side 400 connected to sections on thedielectric layer second side through the via 402. The overall size ofthe antenna 108 can be reduced by printing the radiator on both sides ofthe circuit board.

As shown in FIG. 4 a, the antenna radiator 300 is formed from ameandering rectangular line overlying the dielectric layer first side400, and connected through the via 402 to a meandering rectangular lineoverlying the dielectric layer second side (represented as a dottedline). As shown, the first sections 308 on the circuit board second sideminimally underlie first section 308 on the first side 400, whilesimultaneously, the second sections 312 on the circuit board second sideminimally underlie second sections 312 on the first side 400. However,other arrangements are possible. For example (not shown), the firstsections 308 of the circuit board second side may underlie the firstsections 308 on the circuit board first side 400. Likewise, the radiatorsecond sections 312 on the circuit board second side can underlie thesecond sections 312 on the circuit board first side 400.

As shown in FIG. 4 b, the antenna radiator 300 is formed from ameandering zig-zag line overlying the dielectric layer first side 400,and connected through the via 402 to a meandering zig-zag line overlyingthe dielectric layer second side (represented as a dotted line). Asshown, the first sections 308 minimally underlie first section 308 onthe first side 400, while simultaneously, the second sections 312 on thecircuit board second side minimally underlie second sections 312 on thefirst side 400. Alternately but not shown, the first sections 308 of thecircuit board second side may underlie the first sections 308 on thecircuit board first side 400. As another alternate (not shown), thesecond sections 312 of the circuit board second side may underlie thesecond sections 312 on the circuit board first side 400.

Both figures represent the radiator length to be approximately evenlydivided between the dielectric layer first and second sides. However,the lengths need not necessarily be equal. The invention can be enabledwith other patterns or shapes, FIGS. 4 a and 4 b are merely exemplary.

FIGS. 5 a and 5 b are plan views illustrating a two-sided circuit aspectof the antenna 108 of FIG. 1 with side-alternating first and secondradiator sections 308/312. The antenna radiator first sections 308overlie the dielectric layer first side 400 and the radiator secondsections 312 overlie the dielectric layer second side. The antennaradiator first and second sections 308/312 are connected with aplurality of vias 402. While not always as space efficient as theantennas of FIGS. 4 a and 4 b, the antennas of FIGS. 5 a and 5 b promotedecoupling between the first and second sections 308/312 by forming themon opposite sides of the circuit board. In some aspects, as shown inFIG. 5 b, this increased decoupling permits the first and secondsections to be aligned non-orthogonally, to reduce the form factor whileminimally impacting the antenna performance.

As shown in FIG. 5 a, the antenna radiator first sections 308 and secondsections 312 (represented as dotted lines) form a meandering rectangularline. As shown in FIG. 5 b, the antenna radiator first sections 308 andsecond sections (represented as dotted lines) form a meandering zig-zagline.

Both figures represent the radiator length to be approximately evenlydivided between the dielectric layer first and second sides. However,the lengths need not necessarily be equal. The invention can be enabledwith other patterns or shapes, FIGS. 5 a and 5 b are merely exemplary.

FIGS. 6 a and 6 b are plan views illustrating a two-sided circuit aspectof the antenna 108 of FIG. 1 with side-alternating first and secondradiator section combinations. As above, the radiator 300 includessections overlying the dielectric layer first side connected to sectionson the dielectric layer second side through a plurality of vias 402.More specifically, the radiator 300 includes a plurality of first andsecond section combinations overlying the dielectric layer first sideand the radiator includes a plurality of first and second sectioncombinations overlying the dielectric layer second side.

As shown, the combinations each include one first section and one secondsection, however, the invention is not limited to just this type ofcombination. The radiator combinations on the dielectric layer firstside are connected to the radiator combinations on the dielectric layersecond side (shown as dotted lines) with a plurality of vias 402.

In FIG. 6 a, the antenna radiator first sections 308 and second section312 combinations form a meandering rectangular line. As shown in FIG. 6b, the antenna radiator first sections 308 and second sectioncombinations form a meandering zig-zag line.

Both figures represent the radiator length to be approximately evenlydivided between the dielectric layer first and second sides. However,the lengths need not necessarily be equal. The invention can be enabledwith other patterns or shapes, FIGS. 6 a and 6 b are merely exemplary.

A wireless telephone printed stubby unbalanced dipole antenna has beenprovided. Rectangular and zig-zag patterns have been provided asexamples, however, the invention is not limited to merely thesepatterns. Likewise, examples were given for forming the antenna radiatoron two sides of a circuit board. Again, other combinations are possible.The examples were also given using a consistent type of radiatorpatterning, either rectangular or zig-zag. However, the patterns neednot be consistent. For example, a radiator can be formed form acombination of rectangular, zig-zag, or other non-depicted patterns.Although the antenna has been described in the context of a wirelesstelephone, it has broader application for use in other communicationtechnologies. Other variations and embodiments of the present inventionwill occur to those skilled in the art.

1. A wireless communications device comprising: a circuit boardincluding a first portion and a second portion, the second portioncomprising a dielectric layer having a first side, a second side and aplurality of vias connecting the first side to the second side; and, anantenna comprising a printed conductive line on the second portion ofthe circuit board, the antenna comprising: a first radiator sectionoverlying the first side of the dielectric layer; and a second radiatorsection overlying the second side of the dielectric layer andelectrically connected to the first radiator section by the plurality ofvias, a first end for connection to a transmission line; and a secondunterminated end.
 2. The device system of claim 1 further comprising: achassis with a body; wherein the first portion of the circuit board issubstantially encompassed by the chassis body; and, wherein the secondportion of the circuit board extends outside the chassis body.
 3. Thedevice of claim 2 wherein the chassis body has a first side, a secondside, a top end, and a bottom end; wherein the circuit board firstportion extends from the chassis body first side proximate to the bottomend to the second side proximate to the top end; and, wherein thecircuit board second portion extends through the chassis top endproximate to the second side.
 4. The device of claim 1 furthercomprising: a transceiver mounted on the first portion of the circuitboard, the transceiver having an antenna port.
 5. The device of claim 1further comprising: digital circuitry mounted on the first portion ofthe circuit board.
 6. The device of claim 5 further comprising: atransceiver mounted on the first portion of the circuit board thetransceiver having an antenna port.
 7. The device of claim 1 wherein theantenna is an unbalanced dipole antenna.
 8. The device of claim 1wherein the radiator has an effective electrical length of approximatelya quarter-wavelength odd multiple at the operating frequency.
 9. Thedevice of claim 1 wherein the radiator includes a plurality oforthogonal radiator sections.
 10. The device of claim 1 wherein theradiator is formed in a pattern selected from the group includingmeandering rectangular lines and meandering zig-zag lines.
 11. Thedevice of claim 1 wherein the radiator is formed from a first meanderingrectangular line overlying the dielectric layer first side, andconnected through the plurality of vias to a second meanderingrectangular line overlying the dielectric layer second side.
 12. Thedevice of claim 1 wherein the radiator is formed from a first meanderingzig-zag line overlying the dielectric layer first side, and connectedthrough the plurality of vias to a second meandering zig-zag lineoverlying the dielectric layer second side.
 13. The device of claim 1wherein the first radiator section and the second radiator section forma meandering rectangular line.
 14. The device of claim 1 wherein thefirst radiator section and the second radiator section form a meanderingzig-zag line.
 15. An unbalanced dipole antenna for a wirelesscommunications device, the antenna comprising: a circuit boardcomprising a dielectric layer, the dielectric layer having a first side,a second side, and a plurality of connection vias between the dielectriclayer first side and the dielectric layer second side; a circuit mountedon the circuit board; and, a radiator formed from a printed conductiveline comprising: a first section overlying the first side of thedielectric layer; and a second section overlying the second side of thedielectric layer and connected to the first section through theplurality of connection vias; a first end for connection to atransmission line; and a second unterminated end.
 16. The antenna ofclaim 15 wherein the radiator includes a plurality of orthogonalradiator sections.
 17. The antenna of claim 15 wherein the radiator isformed in a pattern selected from the group including meanderingrectangular lines and meandering zig-zag lines.
 18. The antenna of claim15 wherein the radiator is formed from a first meandering rectangularline overlying the dielectric layer first side, and connected throughthe plurality of connection vias to a second meandering rectangular lineoverlying the dielectric layer second side.
 19. The antenna of claim 15wherein the radiator is formed from a first meandering zig-zag lineoverlying the dielectric layer first side, and connected through theplurality of connection vias to a second meandering zig-zag lineoverlying the dielectric layer second side.
 20. The antenna of claim 15wherein the radiator has an effective electrical length of approximatelya quarter-wavelength odd multiple at the operating frequency.